It is difficult to formulate a personal wash bar which can deliver sufficient skin benefit agent onto skin to provide a perceivable skin benefit and which does not at the same time affect bar processing (e.g., benefit agent may be sticky and clog machinery or may be of high viscosity and render the bar composition difficult to extrude) and/or affect bar user properties (e.g., foaming).
For example, soap bars containing high levels of oils have been claimed in U.S. Pat. No. 3,814,698 to Ferrara et al. However, such soap bars tend to reduce lather performance, are soft and become softer with increased use which makes the bars difficult to use and undesirable to handle. Besides the above undesirable properties, soap bars containing high level of oils are soft and mushy resulting in difficulties in processing through conventional bar extrusion equipment.
Unexpectedly, applicants have found that when the benefit agents are separately incorporated into bars as part of a bar adjuvant comprising (1) benefit agent; (2) a deposition polymer aid (e.g., cationic polymer); and (3) an optional water soluble or dispersible material (e.g., to manipulate rigidity, flowability and dispersibility of additive), enhanced deposition of benefit agent is achieved without affecting processing or comprising lather volume.
The use of deposition polymers, such as cationic polymers, to enhance deposition of a water insoluble particle (e.g., silicone oil) is known in the context of deposition from liquid shampoo onto hair. U.S. Pat. No. 5,037,818 to Sime, for example, teaches cationics to enhance deposition on hair from shampoos.
WO 94/03152 (assigned to Unilever PLC) teaches liquid cleansers that can effectively deposit silicone oil on skin using cationic polymers.
U.S. Pat. No. 4,788,006 to Bolich, Jr. et al. teaches shampoos with silicone particles of 2 to 50 micrometers which compositions contain xanthan gum to condition hair.
None of the above references, however, relate to deposition of benefit agent from bars onto skin using cationic polymers, let alone the use of specific adjuvant compositions comprising benefit agent, deposition aid (e.g., cationic) and optional water soluble or water dispersible materials, wherein the adjuvants can deliver benefits without compromising bar processing and/or bar use properties.
The art has disclosed personal cleansing bars containing conditioning bath oils (see for example, U.S. Pat. No. 3,814,698 to Ferrara). The conditioning oils, however, reduce sudsing and lathering, create processing difficulties in plodding and stamping and are not deposited in compounds sufficient to provide a perceivable skin effect.
The art also discloses personal washing bars comprising cationic polymers to provide a skin conditioning effect and/or mildness (see U.S. Pat. No. 4,673,525 to Small et al.; U.S. Pat. No. 4,820,447 to Medcalf, Jr. et al.; and U.S. Pat. No. 5,096,608 to Small et al.). The cationic is not added to a separate adjuvant powder/chip which is then mixed in with a base chip prior to plodding and extrusion to form final bar. While not wishing to be bound by theory, it is believed to be this formation of a separate concentrated region prior to mixing with base chip which allow enhanced deposition to occur in the subject invention compared to the reference.
U.S. Pat. No. 3,761,418 to Parran, Jr. discloses detergent compositions containing both water insoluble particulate substances and cationic polymers to enhance deposition and retention of the particulate substances on surfaces washed with detergent composition. Specifically, enhanced deposition of antimircobial agents from toilet detergent bar using cationic polymers is disclosed. Again the reference does not teach or suggest the use of cationic polymer and benefit agent in a separate chip/powder prior to mixed with base chip.
In summary, it is known that deposition of water insoluble particles from personal cleansing product can be enhanced using cationic (e.g., use of cationic to enhance antimicrobial deposition from detergent bar). However, when cationic has been used to enhance deposition of oil, deposition has been small and not sufficient for perceivable skin effect. This is because cationic and benefit agent/oil have never been physically separated from the rest of the composition prior to final formation of bar.
Unexpectedly, applicants have found that when benefit agent and cationic polymer are separately formed and later mixed with other bar components, enhanced deposition is obtained. Further, bars prepared using adjuvant chips/powders can be readily processed by conventional bar processes and lather properties are not compromised.
Finally, applicants note that in a copending application U.S. Ser. No. 08/821,501, filed same day as subject application, entitled "Process for Making Bar Compositions Having Enhanced Deposition of Benefit Agent Comprising Use of Specific Spray-Dryable Adjuvant Powders", applicants teach use of a separately prepared adjuvant powder to be mixed with surfactant-containing base chips. The adjuvant of that invention, however, comprise carriers of minimum melting point (80.degree. C. and higher, preferably about 100.degree. C.) and can be prepared only by spray-drying. By contrast, adjuvants of the subject invention can be prepared by spray-drying, freeze-drying and other forms of drying.